This invention relates to an apparatus for sequentially and automatically operating a mobile apparatus such as a powered sprinkling apparatus. The details of the sprinkling apparatus itself are well known. Many types of devices are currently in use, including powered carriages having a single large sprinkling nozzle and elongated sprinkling conduits having a plurality of sprinklers arranged along their lengths. For instance, the present apparatus could be used in combination with the elongated conduits and associated sprinkling devices currently used in center pivot irrigation, where jointed lengths of conduit are arranged in line and are suspended above a field by independently powered carriages. Rather than limiting such sprinkling equipment to use about a fixed center pivot, the present apparatus frees them for travel along a field in a path parallel to a series of stationary supply risers. This permits the sprinkling conduit to apply water to much larger areas than that surrounding a single center pivot. It also permits one to apply the water in a rectangular or irregularly shaped field pattern, eliminating the problems of circular movement and the inefficiency of sprinkling only a circular pattern within a square or rectangular field area.